Valéria Centeno de Freitas

Avaliação diagnóstica da cardiomiopatia hipertrófica em fase clínica e pré-clínica

Hypertrophic cardiomyopathy is a familial, genetic disease caused by mutations in genes encoding sarcomeric proteins. It is characterized by various deGrees of left ventricular hypertrophy, usually diffuse, predominantly involving the interventricular septum. The asymptomatic forms with mild or no segmental hypertrophy makes it difficult to establish the diagnosis and screening for familial forms. Its high penetrance is often incomplete and, as a result, 20% to 30% of adults who carry disease-causing gene mutations do not express the phenotype. The susceptibility to sudden death and likelihood of late expression makes establishing a preclinical diagnosis all the more important. The use of Doppler echocardiography and magnetic resonance imaging, in conjunction with a detailed ECG analysis, may be useful in this process. Molecular genetic studies can identify mutations in 60% to 80% of the cases. However, its complex, time-consuming and costly nature, coupled with an inadequate assessment of genotype-phenotype relationships, limits its routine application. Major advances in imaging methods and the introduction of more simplified molecular techniques may contribute to clinical and preclinical diagnosis of hypertrophic cardiomyopathy, in addition to allowing implementation of therapeutic strategies to prevent or delay the development of the disease.

Ventricular arrhythmias and left ventricular hypertrophy in hypertrophic cardiomyopathy

BACKGROUND In hypertrophic cardiomyopathy (HCM), the degree of left ventricular hypertrophy (LVH) could influence the development of ventricular arrhythmias. OBJECTIVE In HCM, analyze the association between the occurrence of ventricular arrhythmias determined by Holter electrocardiogram (ECG-Holter) and the degree of LVH determined by maximum wall thickness (MWT) in echocardiography and body mass index (BMI). METHODS Fifty-four consecutive patients with HCM underwent 24-hour ECG-Holter and echocardiography for assessment of level of LVH through MWT and BMI. Two levels were established for the occurrence of Ventricular Arrhythmias: I - alone or paired extrasystoles and II - Non- Sustained Ventricular Tachycardia (NSVT). RESULTS In 13 patients (24%) with NSVT (level II), there was a higher frequency of MWT of the left ventricle (LV) > 21 mm (n = 10, 77%, 25 ± 4 mm) and LLLV = 144 g/m² (n = 10, 77%, 200 ± 30 g/m²), in comparison with those presenting with extrasystole arrhythmias (level I) (n = 41, 76%), in which these measures were identified in, respectively, 37 % (n= 15, 23 ± 1 mm), p = 0.023, and 39% (n = 16, 192 ± 53 g / m²) of the cases (p = 0.026). The cut-off values mentioned were determined by the ROC curve with a confidence interval of 95%. NSVT was more common in patients with MWTLV > 21 mm and LLLV > 144 g/m² (8 of 13, 62%) than in those with (4 of 13, 31%) or without (1 of 13; 8%) echocardiographic variables above cut-off values (p = 0.04). CONCLUSION In HCM, occurrence of ventricular arrhythmias by Holter was associated with the degree of LVH assessed by echocardiography through MWT and BMI.

Left Ventricular Diastolic Function in Hemodialysis Patients: Role of Preload Increase Maneuver on Tissue Doppler Imaging Evaluation

Objective: Tissue Doppler imaging (TDI) has recently been proposed as a relatively preload-independent method to evaluate left ventricular diastolic function. We sought to investigate the higher-accuracy of TDI to assess diastolic function in end-stage renal disease (ESRD) patients on hemodialysis (HD) associated with a preload increase maneuver. Methods: Thirty-two consecutiveESRD patients (16 female, ages 48.8 ± 17.5 years, 14 ≤45 and 18 >45 years old) were evaluated. Measurements of E, A velocities and the E/A ratio from transmitral inflow pulsed wave Doppler, and E’, A’ velocities and the E’/A’ ratio from TDI were obtained 1 h before and 1 h after HD at baseline and with a preload increase maneuver. Results: The E/A ratio changed significantly in all patients aged >45 before and after HD with the preload increase maneuver. The E’/A’ ratio increased in all subjects with the preload increase maneuver before HD but did not change with the maneuver after HD in the euvolemic state in all patients. Conclusion: In ESRD patients on routine HD, TDI evaluation associated with a preload increase maneuver proved to be a more accurate method to identify diastolic dysfunction when the evaluation is performed in euvolemic patients after HD.

Prevalence and Phenotypic Expression of Mutations in the MYH7, MYBPC3 and TNNT2 Genes in Families with Hypertrophic Cardiomyopathy in the South of Brazil: A Cross-Sectional Study

Background: Mutations in sarcomeric genes are found in 60-70% of individuals with familial forms of hypertrophic cardiomyopathy (HCM). However, this estimate refers to northern hemisphere populations. The molecular-genetic profile of HCM has been subject of few investigations in Brazil, particularly in the south of the country. Objective: To investigate mutations in the sarcomeric genes MYH7, MYBPC3 and TNNT2 in a cohort of HCM patients living in the extreme south of Brazil, and to evaluate genotype-phenotype associations. Methods: Direct DNA sequencing of all encoding regions of three sarcomeric genes was conducted in 43 consecutive individuals of ten unrelated families. Results: Mutations for CMH have been found in 25 (58%) patients of seven (70%) of the ten study families. Fourteen (56%) individuals were phenotype-positive. All mutations were missense, four (66%) in MYH7 and two (33%) in MYBPC3. We have not found mutations in the TNNT2 gene. Mutations in MYH7 were identified in 20 (47%) patients of six (60%) families. Two of them had not been previously described. Mutations in MYBPC3 were found in seven (16%) members of two (20%) families. Two (5%) patients showed double heterozygosis for both genes. The mutations affected different domains of encoded proteins and led to variable phenotypic expression. A family history of HCM was identified in all genotype-positive individuals. Conclusions: In this first genetic-molecular analysis carried out in the south of Brazil, we found mutations in the sarcomeric genes MYH7 and MYBPC3 in 58% of individuals. MYH7-related disease was identified in the majority of cases with mutation.